Fragmentation of metastable SF6-* ions with microsecond lifetimes in competition with autodetachment

摘要

Fragmentation of metastable SF6-* ions formed in low energy electron attachment to SF6 has been investigated. The dissociation reaction SF6-*-> SF5-+F has been observed similar to 1.5-3.4 mu s and similar to 17-32 mu s after electron attachment in a time-of-flight and a double focusing two sector field mass spectrometer, respectively. Metastable dissociation is observed with maximum intensity at similar to 0.3 eV between the SF6-* peak at zero and the SF5- peak at similar to 0.4 eV. The kinetic energy released in dissociation is low, with a most probable value of 18 meV. The lifetime of SF6-* decreases as the electron energy increases, but it is not possible to fit this decrease with statistical Rice-Ramsperger-Kassel/quasiequilibrium theory. Metastable dissociation of SF6-* appears to compete with autodetachment of the electron at all electron energies. (c) 2008 American Institute of Physics.